3173 results about "Nanofiltration" patented technology

Disclosed in the present invention is a graphene oxide / covalent organic framework nanofiltration membrane. The nanofiltration membrane is prepared by mixing a graphene oxide nanosheet dispersion liquid and an imine covalent organic framework nanosheet dispersion liquid, and performing ultrasonic treatment, suction filtration and heat treatment. Further disclosed are a preparation method for the nanofiltration membrane and a use thereof. According to the present invention, a polymer film is used as a support layer, a covalent organic framework and graphene oxide are loaded on the support layer by means of vacuum filtration, and a cross-linked graphene / covalent organic framework nanofiltration membrane is prepared by a thermal crosslinking reaction after drying. The method involves simple and convenient operations and ingenious design, and the obtained membrane has excellent separation performance. By means of covalent bond crosslinking between the graphene oxide and the covalent organic framework, the structure of the membrane is more compact, thereby increasing the retention rate of the membrane for sodium sulfate and sodium chloride. In addition, covalent organic framework nanosheets provide straight channels for the nanofiltration membrane, thereby significantly improving the water permeability of the nanofiltration membrane.

The invention discloses a method for extracting lithium from a salt lake and an extraction device. The method for extracting lithium from the salt lake provided by the invention comprises the following steps: salt lake brine is subjected to aluminum adsorbent adsorption, ultrafiltration impurity removal, multi-stage nanofiltration magnesium and boron removal, reverse osmosis concentration, ultrafiltration softening deep magnesium removal, resin magnesium and boron removal, MVR evaporation and other technological processes, and a battery-grade lithium carbonate product is obtained. According to the method, the membrane separation technology serves as a core, resin and an evaporation system serve as auxiliary materials, deep separation of magnesium and lithium in the salt lake brine is achieved, the boron removal rate and the lithium recovery rate are high, meanwhile, recycling of water resources is guaranteed, and the whole process has the advantages of being controllable, high in automation degree, low in production cost, small in pollution, high in water recovery rate and suitable for industrial production. The method can be applied to large-scale production of salt lake lithium extraction.

The invention discloses a nanofiltration membrane for extracting lithium from salt lake brine with a high magnesium-lithium ratio and a preparation method of the nanofiltration membrane, and belongs to the technical field of nanofiltration composite membranes. The preparation method of the nanofiltration membrane comprises the following steps: first-time interfacial polymerization treatment, second-time interfacial polymerization treatment and post-treatment. The nanofiltration membrane with a double-layer lithium ion permeation channel is constructed through coupling of secondary interfacial polymerization and a B15C5 modification process, and stable permeation performance of the membrane is guaranteed while high magnesium ion rejection rate and high magnesium-lithium separation factor are realized through synergistic modification of crown ether and secondary interfacial polymerization. The nanofiltration membrane disclosed by the invention shows excellent performance in a real salt lake brine test, and in practical application, the membrane can effectively treat a complex brine system with a high magnesium-lithium ratio; and in a 24-hour continuous test, long-term stability is also shown, and an efficient, stable and feasible solution is provided for lithium extraction of the salt lake brine with the high magnesium-lithium ratio.

The invention provides a preparation method of a polyester loose nanofiltration membrane, and belongs to the technical field of nanofiltration membrane preparation. The preparation method provided by the invention comprises the following steps: dissolving a water-phase monomer in a sodium hydroxide solution to obtain a NaOH solution containing the water-phase monomer; soaking an ultrafiltration membrane in the NaOH solution containing the aqueous phase monomer to obtain an ultrafiltration membrane supporting layer; contacting the ultrafiltration membrane supporting layer with a trimesoyl chloride solution, and carrying out interfacial polymerization reaction to obtain a primary nanofiltration membrane; and carrying out heat treatment on the primary nanofiltration membrane to obtain the polyester loose nanofiltration membrane. The water-phase monomer is a compound which has a non-planar distorted structure and simultaneously contains phenolic hydroxyl groups and alcoholic hydroxyl groups. The method provided by the invention is simple and easy to implement, relatively low in required cost and beneficial to realizing large-scale industrial production of the high-efficiency nanofiltration membrane. The polyester loose nanofiltration membrane prepared by the preparation method disclosed by the invention has relatively high permeation flux, and meanwhile, a relatively high Na2SO4 retention rate can be kept.

The invention discloses a high-selectivity magnesium-lithium separation nanofiltration membrane based on a polyolefin base membrane and a preparation method and application of the high-selectivity magnesium-lithium separation nanofiltration membrane based on the polyolefin base membrane. The preparation method comprises the steps that the polyolefin base membrane is in single-face contact with an organic phase monomer solution containing an isophthaloyl chloride monomer or a paraphthaloyl chloride monomer, and the redundant solution is poured out; one side, contacted with the organic phase monomer solution, of the obtained membrane is contacted with a polyethyleneimine-containing aqueous phase monomer solution, an interfacial polymerization reaction is carried out, the obtained membrane is placed in a drying oven for heat treatment, then the membrane is soaked in an organic solution for activation, and the polyvinyl composite nanofiltration membrane is obtained. The nanofiltration membrane has high magnesium ion interception and high magnesium-lithium separation selectivity in a mixed solution with a high magnesium-lithium ratio, the preparation process is simple, conditions are mild, amplification and industrial production are easy to realize, and the nanofiltration membrane has good long-term operation stability.

The invention provides a PVDF (Polyvinylidene Fluoride) nanofiltration membrane constructed on the basis of microwave-enhanced bridging interfacial polymerization as well as a preparation method and application of the PVDF nanofiltration membrane. The method comprises the following steps: reacting PVDF powder with an organic alkali to prepare a modified film-forming solution, blade-coating the modified film-forming solution on a non-woven fabric supporting layer, placing the non-woven fabric supporting layer in an ethanol-water or methanol-water coagulating bath, and preparing a PVDF supporting film by virtue of assistance of an ice template; weighing the functionalized nano material and an amino silane coupling agent, performing ultrasonic dispersion, and adding a catalyst for reaction to obtain dispersion liquid; immersing a PVDF support membrane into the dispersion liquid to obtain a modified membrane; immersing the modified membrane into an aqueous solution containing an amine monomer and an organic solution containing an acyl chloride monomer, and carrying out microwave radiation. The interface reaction rate and selectivity are enhanced through the microwave excitation effect, and meanwhile, the hydrophilicity and reaction activity of the PVDF base membrane are cooperatively regulated and controlled, so that the separation efficiency and the anti-pollution capacity of the membrane are remarkably improved. The obtained PVDF nanofiltration membrane has high flux, high selectivity and excellent structural stability, and is suitable for efficient purification and resource recovery application in a complex water system.

The invention discloses a high-performance composite solvent-resistant nanofiltration membrane with a rigid twisted non-planar structure polyamide layer and a preparation method of the high-performance composite solvent-resistant nanofiltration membrane. The preparation method comprises the steps of preparation of the rigid twisted non-planar structure polyamide layer and surface modification. A water phase solution containing adamantane diamine and m-phenylenediamine and an organic phase solution containing 1, 3, 5-trimesoyl chloride and acetone are subjected to interfacial polymerization reaction to prepare a polyamide layer with a rigid twisted non-planar structure, and then a polyphenol modifier is used for carrying out hydrophilic modification on the polyamide layer, so that the rigid twisted non-planar structure is obtained. The pure water permeability and retention rate of the solvent-resistant nanofiltration membrane are obviously improved; due to the introduction of adamantane diamine, the interfacial polymerization process and the formation of a polyamide layer are remarkably regulated and controlled, and the separation performance of the solvent-resistant membrane is greatly improved on the premise that the interception performance of the membrane is hardly reduced; the preparation process is simple, and the prepared membrane is excellent in performance and has a good application prospect in the aspect of organic solvent separation.

The present invention relates to the technical field of nanofiltration membranes, and particularly relates to a preparation method for a positively charged nanofiltration membrane for improving a "trade-off" effect. The preparation method comprises the following process: sequentially adding a water phase and an oil phase to the surface of a support layer to perform a reaction, so as to prepare a polyamide layer; pouring in a functionalized graphene dispersion; and sequentially placing same into an N,N-dimethyl propane diamine solution, a sodium borohydride solution and an iodomethane solution to perform a reaction, so as to obtain a nanofiltration membrane, wherein the functionalized graphene is pyrrolidone-based graphene. According to the present invention, a mixture of piperazine and polyethyleneimine is used as a water phase and is subjected to interfacial polymerization with an oil phase 1,3,5-trimesoyl chloride on the surface of the support membrane; and by means of the compounding of micromolecular piperazine and macromolecular polyethyleneimine, the rapid formation of a polyamide layer is promoted, the distance of a system cross-linked network is increased, a positively charged polyamide layer having a large pore diameter and good hydrophilicity is formed, and a good water flux and a good rejection rate are achieved, thereby improving the "trade-off" effect.

The invention relates to a preparation method of a nanofiltration membrane, the nanofiltration membrane prepared by the preparation method and application of the nanofiltration membrane. The method comprises the following steps: preparing a membrane casting solution, curing the membrane casting solution on a support material to form a base membrane, and the membrane casting solution comprises a polymer and a solvent; the base membrane is in contact with a first phase solution and a second phase solution in sequence, the first phase solution comprises a first phase monomer, an adsorbent A, an active agent B and an acid-binding agent C, and the second phase solution comprises a second phase monomer and a cross-linking agent D; and post-processing. The nanofiltration membrane disclosed by the invention has excellent tolerance to high-concentration strong oxidizing acid or mixed acid, still keeps high flux and high salt rejection rate even after being soaked in the high-concentration strong oxidizing acid or mixed acid for a long time, can stably operate for a long time under high pressure, and has high flux and high salt rejection rate at the same time; the method can be effectively applied to the fields of waste acid treatment in the titanium dioxide production process, extraction and separation of lithium battery raw materials, mineral product smelting metal ion and acid recovery and the like for filtration and / or separation.

The invention discloses a preparation method of a photocatalytic nanofiltration membrane based on IL-GQDs. The method comprises the following steps: pretreating bagasse, and applying the pretreated bagasse and imidazole ionic liquid (IL) to preparation of ionic liquid functionalized graphene quantum dots (IL-GQDs); the IL-GQDs are uniformly distributed on the surface of the base membrane by utilizing a vacuum-assisted low-temperature interfacial polymerization technology to form an ultrathin photocatalytic active layer; and finally, curing and cleaning to obtain the photocatalytic nanofiltration membrane based on the IL-GQDs. According to the prepared IL-GQDs, the membrane surface is endowed with high specific surface area and excellent photocatalytic activity, and meanwhile, an additional water transmission channel can be established under the condition that the pore diameter of the membrane is not changed, so that the problem of trade-off of a traditional membrane is solved. In addition, through combination of low-temperature and vacuum-assisted interfacial polymerization technologies, the membrane structure is more uniform and compact, defects on the surface of the membrane are reduced, and the stability and the anti-pollution capacity of the membrane are improved. The membrane disclosed by the invention shows relatively high water flux, salt recovery rate and long-term stability in water treatment application.

The invention discloses a preparation method and application of a polyamide composite nanofiltration membrane containing a graphdiyne middle layer, and belongs to the technical field of membrane separation. Comprising a porous substrate, a graphdiyne middle layer and a polyamide layer. The graphdiyne is selected from graphdiyne, graphdiyne, hydrogen-substituted graphdiyne and other graphdiyne derivatives. The specific preparation method comprises the following steps: carrying out suction filtration on graphdiyne dispersion liquid to a porous substrate, respectively dipping the graphdiyne dispersion liquid in a water phase and an oil phase, carrying out interfacial polymerization to generate a polyamide membrane, and finally, drying the membrane in a constant-temperature and constant-humidity drying oven to obtain the polyamide composite nanofiltration membrane containing the graphdiyne middle layer. The preparation method disclosed by the invention is simple and efficient, and the prepared composite membrane can effectively intercept divalent salt and organic matters in water and has excellent water permeability, ion separation and antibiotic desalination effects.

The invention provides a detoxification method and system based on nanofiltration treatment of lithium ore smelting slag, and the method comprises the following steps: step S1: carrying out acid leaching treatment on the lithium ore smelting slag by using an inorganic acid liquid, so that acid-soluble components in the lithium ore smelting slag are dissolved in the inorganic acid liquid to obtain an acid leaching liquid and detoxified smelting slag; s2, the acid leaching solution is subjected to oxidation treatment, metal ions with intermediate valence in the acid leaching solution are oxidized into metal ions with high valence, and an oxidized acid leaching solution is obtained; s3, carrying out nanofiltration treatment on the oxidized pickle liquor to intercept high-valence metal ions in the oxidized pickle liquor so as to obtain concentrated liquor and permeate liquor; s4, using the permeate liquid as the inorganic acid liquid in the step S1 for acid leaching treatment. According to the method, toxic components in the lithium ore smelting slag can be fully separated, and resource utilization is easier.

The invention relates to a preparation method of a nanofiltration membrane containing a covalent organic framework (COF) interlayer. The nanofiltration membrane (NF) comprises a base membrane, an interlayer and a separation surface layer. The interlayer is formed by in-situ growth of polyphenol and diamine under the action of an oxidizing agent, and the separation surface layer is formed by an aqueous-phase active monomer and multi-element acyl chloride through an interfacial polymerization reaction. According to the invention, an imino covalent organic framework (TpPa-COF) film interlayer is introduced, and a surface polyamide layer is prepared through interfacial polymerization, so that the hydrophilicity of the film and the ability of removing divalent cations are improved. The invention aims to solve the problem of balance between low flux and high separation effect of an NF membrane in separation of monovalent / divalent cations, maintain ideal water flux while ensuring high separation effect, and solve the problem that a traditional NF membrane separation layer has defects. The two-dimensional TpPa-COF material can effectively control the pore size distribution and hydrophilicity of the surface of the substrate and improve the separation performance of the composite membrane. The preparation method is simple, and the obtained nanofiltration membrane has a wide application prospect.

The invention discloses a chlorine-resistant and acid-resistant composite nanofiltration membrane and a preparation method thereof, and belongs to the technical field of membrane separation. A polyhydric alcohol or / phenol compound monomer containing no less than two hydroxyl groups is subjected to interfacial polymerization with cyanuric chloride, so that a relatively loose network structure can be formed, and selective separation of dye and salt is realized. As a hydrochloric acid (HCl) byproduct can be generated in the reaction process, an alkaline compound is added as an acid-binding agent to neutralize HCl and promote the interfacial polymerization reaction, the formed composite nanofiltration membrane structure does not contain amino groups and polyamide bonds sensitive to active chlorine, the reaction sites of the active chlorine are reduced, and the chlorine-resistant stability of the membrane is good. Meanwhile, the polymer film contains a triazine ring structure, and a formed ether bond has good chemical stability, so that the acid-resistant stability of the film is good. The prepared composite nanofiltration membrane has good nanofiltration separation performance, shows good chlorine-resistant and acid-resistant stability, and can be used for separation of dyes / salts.

The invention discloses a preparation method of a crown ether functionalized anti-pollution nanofiltration membrane, which comprises the following steps: soaking a membrane of a commercial nanofiltration membrane in pure water, and coating the surface with a double-end epoxy compound ethanol solution; uniformly coating the surface of the membrane with an aza 12-crown-4 methanol solution; and drying the membrane in an atmosphere of 40-90 DEG C to obtain the crown ether functionalized anti-pollution nanofiltration membrane. The nano-filtration membrane is realized by chemically grafting aza 12-crown-4 on the membrane surface of a commercial nano-filtration membrane by utilizing a double-end epoxy compound; compared with a traditional nanofiltration membrane, the crown ether functionalized nanofiltration membrane provided by the invention has the advantages that the electronegativity of the surface is reduced, and the surface is similar to an aquatic plant molecular brush structure, so that the deposition of pollutants on the surface of the membrane can be effectively improved, and the anti-pollution performance of the membrane is enhanced; meanwhile, due to the complexing effect of 12-crown-4 molecules on lithium ions, the lithium ions can be effectively captured, concentration polarization of the lithium ions on the surface of the diaphragm is improved, and then the magnesium-lithium separation efficiency of the diaphragm is improved.

The invention provides a method and system for salt separation, evaporation and crystallization of printing and dyeing wastewater, and the method comprises the following steps: sequentially carrying out multi-stage synergistic pretreatment on textile printing and dyeing wastewater to remove suspended solids, degrade organic matters and reduce hardness; the pretreated wastewater is subjected to membrane salt separation treatment, and preliminary separation of salt is achieved through reverse osmosis pre-concentration and nanofiltration salt separation; and respectively carrying out evaporative crystallization treatment on the separated high-concentration salt solution to obtain high-purity sodium sulfate and sodium chloride products. According to the method, the salt recovery rate and the product purity are remarkably improved, the energy consumption and the operation cost are reduced, meanwhile, the problems that in traditional printing and dyeing wastewater treatment, salt is difficult to separate, and the crystallization purity is low are solved, and an innovative solution is provided for high-valued resource recovery of industrial wastewater.

The invention relates to the technical field of dye separation, and discloses a loose nanofiltration membrane and a preparation method and application thereof.The loose nanofiltration membrane is prepared from a multi-acyl chloride organic solution and an amine monomer water-phase solution on the surface of a porous supporting membrane through a one-step interfacial polymerization method, and the rejection rate of the loose nanofiltration membrane to methyl blue, Congo red and other dyes is 95% or above; meanwhile, the loose nanofiltration membrane has high water permeability and excellent dye / inorganic salt separation selectivity, and is expected to have wide application prospects in the fields of dye production and purification and dye wastewater desalination.

The invention provides a high-flux chlorine-resistant anti-pollution composite nanofiltration membrane and a preparation method and application thereof, and the preparation method comprises the following steps: immersing a porous base membrane into a water-phase monomer solution, taking out the porous base membrane, removing a surface solution, and immersing the porous base membrane into an organic-phase monomer solution to complete interfacial polymerization to obtain an initial polyamide active layer; immersing the prepared initial polyamide active layer in a mixed solution containing sodium lignin sulfonate, a surfactant and a catalyst to complete surface modification; and carrying out thermocuring on the prepared surface-modified polyamide active layer to obtain the high-flux chlorine-resistant anti-pollution composite nanofiltration membrane. The anti-pollution performance and water flux of the prepared composite nanofiltration membrane are obviously improved, the composite nanofiltration membrane is suitable for being used as drinking water terminal treatment, and softening and purification of drinking water are achieved.

The invention relates to a preparation method of a nanofiltration membrane, the nanofiltration membrane prepared by the preparation method and application of the nanofiltration membrane. The method comprises: treating a base membrane having a polyamide layer thereon to convert acyl chloride groups in the polyamide layer into carboxyl groups, the base membrane comprising a reinforcing material layer and a polymer layer; activating the carboxyl group, wherein the activating treatment is carried out by using a solution containing a carboxyl group activating agent; contacting with a solution containing amino polyethylene glycol substances; contacting with a solution comprising a cross-linking agent; contacting with a solution comprising at least one of a polyhydroxy polymer and a polyhydroxy compound. The method is simple and easy to operate, reaction parameters are easy to regulate and control, and continuous industrial production can be achieved. The nanofiltration membrane prepared by the invention has stable and excellent comprehensive performance (permeability, separation performance, pollution resistance, scratch resistance and thick net bruise resistance). The nanofiltration membranes of the invention can be advantageously used for filtration, separation, and / or concentration.

The invention relates to the technical field of industrial production wastewater treatment, and particularly provides a resource utilization method of calcium chloride high-salt water containing high-concentration organic matters. The method comprises the steps of pretreatment, wet catalytic oxidation, salt type conversion, softening filtration, deep oxidation, nanofiltration purification and targeted adsorption, no residual mother liquor exists, no secondary pollution is generated, organic matters in effluent are stable and reach the standard, the water quality and water quantity fluctuation resistance is high, heterogeneous and homogeneous catalysts are combined for catalysis, and the purification effect is good. According to the method, the sodium chloride solution is used as a raw material, the homogeneous catalyst is recycled, in addition, most of salt in the homogeneous catalyst is also recycled, resource reutilization is fully achieved, the treatment cost is reduced, and the treated sodium chloride solution can be used as primary saline water for subsequent ion membrane electrolysis.

The invention discloses a piezoelectric nanofiltration membrane with an electric anti-scaling function and a preparation method and application thereof, and belongs to the technical field of membrane method water treatment. Two-dimensional conductive nanosheets are doped in a traditional PVDF piezoelectric membrane, phase separation is performed in an alternating electric field, then a piezoelectric base membrane with high beta-PVDF content and a crystal orientation structure is prepared, and then interfacial polymerization is performed on the piezoelectric base membrane to form the nanofiltration membrane with piezoelectric activity. By adding the two-dimensional conductive nanosheets into the base film, on one hand, the content of beta-phase PVDF in the base film is increased, so that the piezoelectric property of the base film is enhanced; on the other hand, the two-dimensional conductive nanosheets are induced to be directionally arranged and form conductive synapses on the surface of the base membrane by synchronously applying an alternating electric field in the membrane preparation process, so that after interfacial polymerization, the conductive synapses can penetrate into a polyamide layer and form a conductive network, and finally a piezoelectric signal of the base membrane is conducted to the surface of the nanofiltration membrane; therefore, the nanofiltration membrane is endowed with piezoelectric characteristics and an electric anti-scaling function.

The invention discloses a method for extracting lithium from gas field produced water with a high sodium-lithium ratio, and belongs to the technical field of chemical engineering. The mass ratio of sodium to lithium in the gas field produced water is (100-1000): 1, and the method comprises the following steps: S1, nanofiltration: carrying out nanofiltration on the gas field produced water, and intercepting divalent ions to obtain nanofiltration produced water and nanofiltration concentrated water; s2, adsorbing and extracting lithium, namely adjusting the pH value of the sodium-filtered produced water, treating the sodium-filtered produced water through a lithium-sodium adsorption and separation device filled with an adsorbent to realize sodium-lithium separation, and collecting the adsorbed lithium-extracted produced water; s3, desorption of lithium ions: eluting the adsorbent with an acid solution to desorb the lithium ions from the adsorbent, and collecting an eluent; s4, concentration: carrying out reverse osmosis treatment on the eluent, and treating the reverse osmosis concentrated solution through an electrodialysis device to obtain a concentrated lithium-containing concentrated solution; and S5, lithium precipitation: adjusting the pH value of the lithium-containing concentrated solution, adding a lithium precipitation agent, and crystallizing and precipitating lithium to obtain industrial-grade lithium carbonate. The process is simple, the lithium recovery rate during lithium precipitation can be effectively increased, and full-automatic continuous operation can be achieved.

The invention discloses a printing and dyeing wastewater advanced treatment and salt control recycling process and system, and belongs to the technical field of wastewater treatment. According to the process, the printing and dyeing wastewater is sequentially subjected to pretreatment of grating interception, adjustment and homogenization, and coagulating sedimentation; carrying out hydrolytic acidification and biochemical treatment in a membrane bioreactor; softening treatment of ozone oxidation complex breaking and fluidization crystallization softening; carrying out nanofiltration separation to obtain a permeate and a concentrated solution; carrying out seed crystal fluidization descaling on the concentrated solution; respectively carrying out membrane concentration on the nanofiltration permeate and the descaled concentrated solution through reverse osmosis to obtain sodium chloride and sodium sulfate concentrated solutions; and finally, carrying out evaporation curing treatment on the sludge and the crystallized waste residues. Through multi-step cooperative treatment, deep purification of the printing and dyeing wastewater and efficient separation and recycling of salt are realized, and the problems of impure nanofiltration salt separation and high system scaling risk in the prior art are solved.

The invention discloses a surface-enhanced tryptophan modified nanofiltration membrane as well as a preparation method and application thereof. Belongs to the field of water treatment membrane preparation. The invention aims to solve the technical problems of non-uniform pore size distribution and surface hydrophobicity of the conventional nanofiltration membrane. The method comprises the following steps: adding tryptophan into a piperazine water-phase solution, and carrying out interfacial polymerization with oil-phase trimesoyl chloride to prepare the tryptophan modified nanofiltration membrane. According to the preparation method, the diffusion rate of the piperazine monomer can be adjusted in the interfacial polymerization process by utilizing a similar surfactant structure of tryptophan, meanwhile, the tryptophan has hydrophilicity and can improve the hydrophilicity of the surface of an active layer, and the prepared modified nanofiltration membrane is reduced in molecular weight cut-off, improved in surface hydrophilicity and good in water resistance. The retention rate of organic micro-pollutants is improved, and meanwhile, good anti-pollution performance is achieved.

The invention belongs to the technical field of membrane separation, and particularly relates to a nanofiltration membrane for efficient salt dyeing separation and a preparation method and application thereof.The preparation method comprises the following steps that 1, ionic liquid and water are mixed to obtain a mixed solution, cycleanine is dissolved in the mixed solution to obtain a water-phase solution, and the water-phase solution is filtered to obtain a filtrate; pouring the water-phase solution to the surface of the base membrane and completely infiltrating the water-phase solution; and 2, dissolving isophthaloyl dichloride in normal hexane to obtain an organic phase solution, pouring the organic phase solution to the surface of the membrane treated in the step 1, and carrying out an interfacial polymerization reaction to obtain the nanofiltration membrane for efficient salt dyeing separation. According to the preparation method disclosed by the invention, the nanofiltration membrane prepared by taking cycleanine and isophthaloyl dichloride as monomers through interfacial polymerization has a highly-ordered honeycomb nanopore structure, charges on the surface of the membrane are close to neutral, and the ionic liquid added into a water-phase solution further improves the hydrophilicity of the surface of the membrane; the permeation flux and selectivity of the membrane can be effectively improved.

The invention discloses a printing and dyeing wastewater zero-discharge treatment process based on low-pressure high-power membrane concentration and salt separation synergy. The wastewater is sequentially subjected to the steps of double-alkali softening pretreatment, organic pollutant treatment, forward osmosis low-pressure high-power concentration treatment, salt separation treatment and evaporative crystallization. Wherein the forward osmosis low-pressure high-power concentration treatment is performed in a partitioned manner along the flow direction, the osmotic pressure difference is gradually increased, the transmembrane pressure difference is gradually decreased, and interface electrochemical buffer and low-frequency gas-liquid disturbance can be set to inhibit concentration polarization and pollution. Carrying out nanofiltration and salt separation on the concentrated solution to obtain two paths of saline water mainly comprising Na2SO4 and NaCl, and respectively carrying out evaporative crystallization on the two paths of saline water; and refluxing and reusing the water produced by the draw solution. According to the process, high-power concentration and stable salt separation are realized under low mechanical pressure, the energy consumption is reduced, the water recovery rate and the crystal purity are improved, and zero discharge of wastewater is realized.

The invention relates to the technical field of water treatment equipment, in particular to a coaxial nested ultrafiltration and nanofiltration integrated water purification device and system.The coaxial nested ultrafiltration and nanofiltration integrated water purification device comprises a main shell, and an annular ultrafiltration treatment area and an inner nanofiltration treatment area are coaxially arranged in the main shell. An energy storage adjusting assembly is arranged in the nanofiltration treatment area and comprises an elastic breathing sleeve coaxially arranged outside the nanofiltration membrane assembly in a sleeving mode. The sleeve elastically expands during filtering, so that the effects of buffering pressure and storing energy are achieved; and turbulent flow convex ribs can be arranged on the inner wall of the sleeve, so that the nanofiltration membrane is physically cleaned when the sleeve retracts. Besides, a backwashing pipeline and a valve are arranged, linkage control is carried out when the control unit detects that expansion of the sleeve exceeds the limit, and ultrafiltration produced water stored on the nanofiltration side is reversely pushed by utilizing pressure energy released by retraction of the sleeve so as to backwash an ultrafiltration membrane. According to the invention, the cooperation of pressure buffering, online cleaning of the nanofiltration membrane and energy storage backwashing of the ultrafiltration membrane is realized, the operation is stable, the efficiency is high, and the energy is saved.

The invention discloses a low-temperature multi-effect evaporation-based impurity salt treatment process method, and relates to the technical field of industrial waste salt treatment in the chemical industry. According to the scheme, firstly, impurity salt is dissolved and then pretreated by a fluorine removal tank and a multi-medium filter, and pretreated saline water is obtained; then, organic matters and dissolved substances are removed through a catalytic oxidation and nanofiltration device, and a monovalent salt solution and a divalent salt solution are separated out; then, the monovalent salt solution is subjected to reverse osmosis concentration and then enters a low-temperature multi-effect evaporation system for sodium chloride crystallization, and the divalent salt solution is subjected to catalytic oxidation and then enters low-temperature multi-effect evaporation for sodium sulfate crystallization. And finally, the mother liquor subjected to low-temperature multi-effect evaporation is refluxed and retreated, and resources are further concentrated. According to the invention, the waste salt treatment efficiency is effectively improved by optimizing the chemical addition of the sedimentation tank. By adopting a low-temperature multi-effect evaporation technology, the energy efficiency is optimized, the energy loss is reduced, the crystallization efficiency is improved, and the resource recovery rate is increased. And a mother liquor backflow retreatment mechanism reduces waste liquid discharge and reduces environmental burden.

The present invention provides a system and method for extracting lithium from salt lake brine and preparing battery-grade lithium carbonate. The system includes a coagulation and precipitation system, a filtration system, an adsorption and desorption system, a calcium and magnesium removal system, a boron removal system, a concentration system, an evaporation system, and a lithium precipitation system connected in sequence. The calcium and magnesium removal system includes a first-stage reverse osmosis concentration unit, a first-stage nanofiltration calcium and magnesium removal unit, a second-stage reverse osmosis concentration unit, a multi-stage nanofiltration calcium and magnesium removal unit, and a calcium and magnesium ion exchange unit connected in sequence. The boron removal system includes a first-stage nanofiltration boron removal unit, a multi-stage nanofiltration boron removal unit, and a boron ion exchange unit connected in sequence. After the lithium precipitation system, there are also a precision filtration system and a water washing and drying system connected in sequence. By adopting the process of the present invention, the lithium recovery rate is improved, and the product is battery-grade lithium carbonate, greatly improving the resource utilization and recovery rate of the lithium extraction system, reducing the amount of externally added water and the consumption of sodium carbonate in the process of the lithium precipitation system.

The application provides application of a temperature-sensitive composite material in preparation of a separation membrane, a nanofiltration membrane and a preparation method, and particularly relates to the technical field of separation membranes. The temperature-sensitive composite material comprises a temperature-sensitive material and conductive fillers. The mass ratio of the temperature-sensitive material and the conductive fillers is 10-30:1-10. The application utilizes the characteristic that the temperature-sensitive material quickly responds to temperature changes, and the temperature-sensitive material transmits to the outside world through the conductive fillers, so that timely feedback and adjustment of the temperature in the preparation process of the separation membrane are realized, the isotropic separation membrane is prepared, the stability of the performance of the separation membrane is ensured, and the quality of the separation membrane product is improved.